1
GATE EE 2018
Numerical
+2
-0
The equivalent circuit of a single phase induction motor is shown in the figure, where the parameters are

R1 = R2' = Xl1 = Xl2' = 12 $$\Omega$$, Xm = 240 $$\Omega$$

and s is the slip. At no-load, the motor speed can be approximated to be the synchronous speed. The no-load lagging power factor of the motor is___________ (up to 3 decimal places).
2
GATE EE 2017 Set 2
Numerical
+2
-0
A star-connected, 12.5 kW, 208 V (line), 3-phase, 60 Hz squirrel cage induction motor has following equivalent circuit parameters per phase referred to the stator. R1 = 0.3 Ω, R2 = 0.3 Ω, X1 = 0.41 Ω, X2 = 0.41 Ω. Neglect shunt branch in the equivalent circuit. The starting current (in Ampere) for this motor when connected to an 80 V (line), 20 Hz, 3- phase AC source is __________.
3
GATE EE 2017 Set 1
Numerical
+2
-0
A 375W, 230 V, 50 Hz capacitor start single-phase induction motor has the following constants for the main and auxiliary windings (at starting): $$Z_m=\left(12.50\;+\;j15.75\right)\;\Omega$$ (main winding), $$Z_a=\left(24.50\;+\;j12.75\right)\;\Omega$$(auxiliary winding). Neglecting the magnetizing branch the value of the capacitance (in µF ) to be added in series with the auxiliary winding to obtain maximum torque at starting is _______.
4
GATE EE 2015 Set 2
Numerical
+2
-0
A 220 V, 3-phase, 4-pole, 50 Hz inductor motor of wound rotor type is supplied at rated voltage and frequency. The stator resistance, magnetizing reactance, and core loss are negligible. The maximum torque produced by the rotor is 225 % of full load torque and it occurs at 15% slip. The actual rotor resistance is 0.03 Ω/phase. The value of external resistance (in Ohm) which must be inserted in a rotor phase if the maximum torque is to occur at start is ______.